Stephen Green, who was boss of HSBC during the period covered by the leaked Swiss files, emerged from the global financial crisis with a reputation as the City of London’s ethical banker.

It was an image he actively encouraged. An ordained Church of England minister, Lord Green published a book in 2009 entitled Good Value: Reflections on Money, Morality and an Uncertain World. It preached that business leaders should behave not just legally but ethically, going beyond “what you can get away with”.

Today, Green faces awkward questions over the culture of lax controls and failures in compliance at HSBC’s Swiss bank. The Geneva subsidiary that routinely allowed clients to withdraw very large sums of cash and that colluded with some to conceal undeclared “black” accounts was created on Green’s watch.

The son of a Brighton lawyer, Green began his 28-year career at what was then Hongkong and Shanghai Banking Corporation in 1982. By 1998 he had been singled out for promotion by Sir John Bond, the chairman whose leadership set HSBC on the path to becoming Europe’s largest bank. Green was appointed to the board of HSBC group that year, running investment banking, asset management and crucially, private banking. He retained oversight of the private bank until becoming chief executive.

A year later, HSBC bought the Republic National Bank of New York, the business that was merged with other HSBC units to become the new Swiss operation. From2005, Green was afforded an even closer look at the inner workings of the Geneva business as chair of its supervisory company, HSBC Private Banking Holdings (Suisse) SA.

But he has so far refused to answer questions on the scandal, telling the Guardian: “As a matter of principle, I will not comment on the business of HSBC, past or present.”

The principles Green extolled in his book proposed a different approach to corporate good behaviour. “For companies, where does this responsibility begin?” he asked. “With their boards, of course. There is no other task they have which is more important. It is their job – and one which by its nature will never be complete – to promote and nurture a culture of ethical and purposeful business throughout the organisation.”

Green was chief executive of HSBC group from 2003 until being appointed its chairman in 2006. At David Cameron’s invitation he left to join the House of Lords at the end of 2010, donning ermine as Lord Green of Hurstpierpoint and becoming minister for trade and investment.

Green, who became a Church of England priest in 1988, voluntarily gave up his HSBC bonus during the banking crisis, but after long years at the bank he also amassed a £19m pension pot – large even by City standards.

Despite being richly rewarded for his role, Green has never been grilled over the goings-on in Geneva. On the contrary, he left the private sector to a chorus of praise after steering HSBC safely through the global financial meltdown.

Unlike the Royal Bank of Scotland and Lloyds Banking Group, HSBC was not forced to turn to British taxpayers for help. As one of the world’s strongest banks, it remained a rare provider of liquidity to the markets and, when in need of cash – a chunky £12.5bn of it – investors were more than happy to stump up.

“In Stephen we will be appointing a minister with a long career as a leading international banker,” business secretary Vince Cable trumpeted when Green joined his department in 2011, “one of the few to emerge with credit from the recent financial crisis, and somebody who has set out a powerful philosophy for ethical business.”

A source close to Cable said Green’s appointment as trade minister had been made by Cameron. Contacted by the Guardian on Monday as to his view on his former junior ministerin the light of the HSBC revelations, Cable said: “We simply don’t know at present if Lord Green was aware of or condoned these practices.”

Regulators began to catch up with HSBC in 2012, when the US fined the bank $1.9bn for allowing its international branches in Mexico and elsewhere to become a conduit for “drug kingpins and rogue nations”.

With Green leading trade missions to Mexico and Colombia at the time, there were calls from Labour in opposition for a full explanation. But the minister said he had no plans to quit.

“HSBC has expressed regret that there were failures at implementation ... and I share that regret,” Green said in a letter to Chris Leslie, financial secretary to the UK Treasury for Labour

By the end of 2013, however, Green had left government after two years in post. The prime minister stood by his decision to appoint Green on Monday, saying: “Stephen Green was an excellent trade minister, he did a good job. But I’d also add no government has done more than this one to crack down on tax evasion and aggressive tax avoidance.”

Labour MP Margaret Hodge, chair of parliament’s influential public accounts committee, is due to grill the country’s most senior tax collector, HMRC chief executive Lin Homer, and Indra Morris, director general for tax and welfare at the Treasury, on Wednesday. She has now told Sky News that she is willing to call Green to parliament to account for the HSBC files.